This invention relates generally to projectiles used for marking a target and more particularly to those that contain chemiluminescent compounds that, upon impact of the projectile with the target, create a luminescent spot on the target.
The sport of paintball has become one of the fastest growing sports in the world. The participants carry gas-charged pistols or rifles that can shoot non-lethal projectiles known as paintballs. These paintballs are hollow spheres typically made of a frangible material such as gelatin. The cavity of the sphere contains a colored liquid that is released when the sphere is crushed as the paintball impacts its target. A player loses when she has been hit, as evidenced by a spot of paint left on her body from the impacting paintball.
The sport has been traditionally a day time activity. However, there is increasing demand for night time matches. One problem with practicing paintball at night is the difficulty in seeing the spot of paint on a player that has been hit. This allows a player to xe2x80x9ccheatxe2x80x9d by continuing to play even when she has been hit, because the other players cannot see the spot of paint on her body. One proposed solution to this problem is the use of a luminescent paintball as described in U.S. Pat. No. 5,018,450 to Smith (the xe2x80x98Smith patentxe2x80x99). The Smith patent describes a projectile having two separate hemispheres which are fused together to form an accurate sphere, where each hemisphere contains one of two reactive chemicals which, upon impact and destruction of the spheres, can mix to become a chemiluminescent light source. However, this proposed solution has several shortcomings.
The light output from a chemiluminescent reaction depends greatly upon the ratio of the amounts of oxalate and activator, two compounds that when mixed cause the reaction. In particular, the ratio may not be 1:1. It may be desirable to have a much larger volume of the oxalate and a small volume of highly concentrated activator, to give sufficient intensity and duration to the light output. In such a case, the two hemispheres of the paintball in the Smith patent will not be uniformly filled with the compounds as one side will be relatively empty compared to the other side. This may cause the paintball to become unstable and thereby not travel in the desired trajectory when it has been shot at high speed.
Another problem with the paintball design in the Smith patent is that filling the two hemispheres with oxalate and activator and then sealing them together, as part of a large volume manufacturing process, may be prohibitively expensive.